MISCIBILITY BEHAVIOR OF TERNARY POLY(METHYL METHACRYLATE) POLY(ETHYL METHACRYLATE) POLY(P-VINYLPHENOL) BLENDS

The phase behavior of ternary blends consisting of poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(p-vinylphenol) (PVPh) was investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The assessment of miscibility was based mainly on the presence of a single glass transition. In this ternary blend where PVPh is miscible with each of the other components, more than 60 wt % PVPh was required to cause miscibility between PMMA and PEMA. Based on the glass transition temperature data, a ternary phase diagram was constructed. The miscibility behavior of the ternary PMMA/PEMA/PVPh blends as well as of the PMMA/PEMA/poly(vinylidene fluoride) (PVF2) and PMMA/PEMA/ poly(styrene-co-acrylonitrile) (SAN) systems was rationalized using the spinodal condition and the Flory-Huggins theory in an attempt to test the validity of this theoretical approach for these systems. Values of the interaction energy between PMMA and PEMA, which correlate quite well between them, were derived from the experimental ternary diagrams. A prediction of the miscibility behavior for ternary PMMA/PEMA/poly(styrene-co-maleic anhydride) (SMA) blends was attempted based on these values.